<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h1>jsonp</h1>
    <button id="btn">发送jsonp请求</button>
    <script>
        function callback(data){
            console.log('callback执行了,参数是',data);
        }

        const oBtn = document.getElementById("btn");
        let oScript = null;
        oBtn.onclick = function(){
            if (oScript) {
                oScript.remove();
            }
            oScript = document.createElement('script');
            oScript.src = "http://127.0.0.1:3000/getUser?userId=001&cb=callback";
            document.body.appendChild(oScript);
        }
    </script>
</body>
</html>